Continuous-current dynamo



F. KESSELRING.

CONTINUOUS CURRENT DYNAMO.

APPLICATION FILED IIINE I2, I92o.

1,389,051, PanIeaAug. 30,1921.

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FRITZ xEssELnrNG, or NEUHAUSEN, SWITZERLAND.

i CONTINUOUS-CURRENT DYNAMO.

Original application ledJ'uly 17,1916, Serial No. 109,800. Divided and.this application filed June 12,

1920. Serial No. 388,699.

To all whom t may concern:

Be it known that I, FRITZ'KEssELRING, a citizen of the SwissConfederation, residing at Neuhausen-on-the-Rhine, Switzerland,haveinvented a new and useful Continuous- Current Dynamo, for which Ihave filed applications in Austria May 18, 1916; in Great Britain June8, 1916; in Hungary June 9, 1916, -oi" which the following is aspecification..

The invention relates to variable speed generators, where anapproximately constant voltage is to be obtained at variable speed,without the provision of accessories, such as controlling resistances orthe like.

It is an object of the invention to provide specialk means for obtainingautomatic regulation of the generator during speed variations, so thatat all times a constant voltage may be obtained, such as is necessary intrain l illumination, wherethe eneratorV is driven bythe shaft of therunning wheels. Y

To the accomplishment of the principal object and others that willybecome apparent upon perusal yoi the specification and claims forming apart thereof, the perferred embodiments or' the invention areillustrated in the accompanying drawing, in which Figures 1 and 2illustratethe curves of the different magnetic fluxes in the dynamo.`

Fig. 3 indicates a two pole dynamo having main and auxiliary` poles, thelatter being provided with two sets of'field coils.

Fig. lindicates the dynamo provided with main and auxiliary poles, andan armature having two separate windings.

rThis invention is a division of my copending application for LettersPatent o1 the United States, for improvements in continu.-

ous current dynamos, filed July 17, 1916,

Serial No.1109,8 00 patented July 13, 1920 No. 1,346,213. e

The E. M. F. E'zClqm, wherein- E is the E. M. F. induced in theVarmature of a generator, y y

q: the resultant lmagneticlux of the armature per pole Lpitch (peripheryofv the armature divided bythe number of poles),V

a. the number of revolutionsper minute, and'C, a constant.y Y y It isimmaterial in what mannerthe magnetic flux qais produced, and either anelectromagnet, rora permanent magnet, or a combination of both may beadopted, constituting the field poles of the machine, To obtain aconstant E. M. F. when the speed Varies, it is necessary, of course,that the product Clcpa should remain constant, and in viewl of the factthat the speed varies, qv must change, such that the product will alwaysremain the same, in other wordsfe must vary inverselyas the number ofrevolutions n. To'accomplish this end, the'magneticv flux e 1s producedin the present instance' l by at least two component fluxes, namely (1)aconstant main liux cpl', which is produced either by a permanentmagnet, or by an approximately yconstant number of ampere Specificationof Letters Patent. Patented Aug. 30, 1921.'

turns, or by a combination of both, and (2) v a variable, auxiliary flux92 directed oppositely to the main flux cpu and produced by a number ofampere turns aww, computed according to the formula: awnzCzn-C3, whereinC203 are constants and the constant C3 may be zero. v

The ampere turns of the auxiliary field poles, constitutingthe M. M. F.C201 and producing the magnetic flux e2 `varies directly as the numberof revolutions, whereas the M. M. F. C3 is approximately constant. Thepart C27?, directly in proportion to the speed produces in the air spacea flux opposite to thedirection of the flux cpl, produced by the mainlieldpoles. The portion C3 of the ampere turns provided on the auxiliaryfield poles isarranged to produce a magnetic flux of the same directionas the main flux. The ampere turns C3 can, of course, also ybe replacedeither wholly or in `part by a permanent magnet, or, if preferred, theymay be entirely dispensed with.

lf C3; were Zerothe e-curve would have the number of revolutions andwould therefore not give a constant voltage. This curve would also makenecessary a large and Vcostly dynamo and for this reason itis importantthat C3 is dilierentirom zero.'y l

The approximately constant ampere turns of the main field polesproducing the main flux :phare obtained in the `known manner by one ormore windings energized by an approximately constant voltage. Ortheiflux is `obtained by a permanent magnet, constituting'main eldpoles, or by a combination of both arrangements.Y A,The same applies to.the ,Cnstant portion C3 0f the eMail-ier; flux.

l adapted for direct current or a portion of such a winding to rotate ata speed proportional to the number of revolutions of the generator in anapproximately constant magnetic field (for instance the main magneticflux of the generator), and by applying the induced voltage of one ormore exciter windings.

Another modification embodies the regulating of auxiliary poles so thatthey become magnetized by the armature winding or by conducting thecurrent of the armature around the auxiliary poles, or a combination ofboth lmeans may be provided. In both cases the current of the armatureis not constant and varies approximately proportional to the number ofrevolutions. 'These modifications, therefore, are of secondaryimportance and will only be resorted to in the case of small' typemachines.

The two fiuxes P1 and 2 may iow in entirely different paths, and in thiscase care is to be taken that the conductors of the armature of thedynamo should cut both fluxes. Conversely, the fluxes 151 and P2 mayfiow in paths a portion of which is common to both fluxes, and similarlyfluxes can be set up by spaced poles to flow through the same yoke andthe samel armature (Fig. t).

Referring to the drawings, Figs. 1 and 2 show the graphic curves of thedifferent magnetic fluxes lin the dynamo. b1 is the approximatelyconstant main magnetic flux, f/ 2 the variable auxiliary magnetic fluxand fr the resulting` flux. The number of revolutions n varies betweennl and n2, constituting the range of speed variations for the dy'- namo.C201 and C3 are the M. M. F.s which produce the auxiliary flux. Thecurve f/ 2 is no other than the magnetization curve of. the magneticcircuit of the auxiliary flux. By a suitable selection of substance(air, cast steel, gray iron, armature iron, etc.,) as well as ythetransverse section of the auxiliary magnetic flux circuit, it ispossible, as known, to change the form of the curve 412. Consequently,it is always possible to obtain a curve 15 which is nearly inverselyproportionate to the number of! revolutions.' In Fig. 2 it isassumed'for the sake of. example that l 1 is not exactly constant butrises slightly with an increasing number of revolutions. In this casealso by choosing an appropriate characteristic for the auxiliarymagnetic crcuit it is possible toobtain a good ab curve.

- In Figs. 3 and 4L the application of the invention is diagrammaticallyillustrated. The generator shown in Fig. 4 comprises the armature A andproduces the main magnetic fiux f/l'an'd the auxiliary flux (/)2 bymeans of field coils El, E2, E2. The main armature winding IV, isconnected with the armature brushes K1 and K2. The auxiliary winding 72is connected to the commutator brushes K., and K4. In Fig. 3, K3 is anauxiliary brush on the main commutator. In order to simplify thediagrammatic views all switches have been omitted.

The generator indicated in Fig. 3V comprises a two pole dynamo electricmachine, the main brushes K1 and K2 being in the neutral Zone. In eachpole pitch a main pole producing the flux d, and an auxiliary poleproducing the flux l 2 are arranged. Between the main brushes anauxiliary brush K2 is provided onthe commutator. The armature isequipped with one armature winding only. The main pole isy adapted toproduce an approximately constant magnetic flux, whereas the auxiliarypole produces a variable magnetic flux flowing in a direction oppositeto that of' the main flux. The main pole is equipped with they mainfield coil E2, connected to the brushes K1 and K2. The auxiliary pole isequipped with two field coils E2, E2, of which the former is connectedwith the brushes K1 and K2. As the armature coils between the brushes K1and K2 cut only the approximately constant 'fiux d), it is evident thatbetween K1 and K2 a voltage C27@ isproduced proportional to the` numberof revolutions. The field coil E3 is connected 4to a source ofapproximately constant E. M. F. such as the main brushes K1 and K2 or astorage battery to produce a constant M. M. F. C3 tending to set up aflux of the same direction as el. rlhe magnetizing effect of the coil E2being opposed to that of' the coil E1 and the magnetization curve of theauxiliary magnetic circuit being chosen as shown in Figs. 1 and 2 it isevident that between the brushes K1 and K2 an approximately constantvoltage is produced. y

llhe dynamo illustrated in Fig. 4 comprises main poles and auxiliarypoles admitting the main flux q21 and the auxiliary flux o2respectively. provided with two windings, namely, the main armaturewinding W1 equipped with the commutator brushes K1 and K2 and anauxiliary armature winding W2 having the commutator brushes K2 and K4.The main winding is adapted to revolve within both magnetic iuxes cp1and e2, the auxiliary The armature A is.

winding W2 is adapted to revolve only within the constant flux e, so asto produce a voltage which is proportional to the numbervof revolutions.The main pole contains a main field coil E1 connected to the mainbrushes K1 and K2 and producing the approximately constant magnetic fluxcpl. The field coil E2 of the auxiliary `pole is impressed with thedifference of voltage existing between the auxiliary armature windingand the main armature winding. The voltage of the auxiliary armature isproportional to the number of revolutions and the voltage of the mainarmature is approximately constant. It kis therefore evident that the M.M. F. of the auxiliary pole is Czar-C3. The magnetizing effect of theauxiliary field coils is opposed to that of the main field coils and inView of the magnetization curve ofthe auxiliary pole (Figs. 1 or 2) itis evident that the voltage produced by the main armature winding isapproximately constant.

It is within the scope of the invention to provide on the auxiliary polein addition to the field coil E2 a third field coil energized by themain armature winding, to increase the constant C3.

If a strictly constant voltage is not required, but rather a voltagewhich rises or falls slightly with the number of revolutions, this maybe obtained by a suitable selection of the materials, etc., for theauxiliary magnetic circuit. For example, in the case of trainillumination it is sometimes required that upon greater speed the lightsshould shine brighter, and in such cases the voltage is permitted torise slightly with the increasing number of revolutions. It is, ofcourse, impossible to produce a cp curve which conforms closely to theideal cp curve, and for this reason certain deviations from the desiredvoltage curve must be taken into consideration.

What I claim is 1. A variable-speed continuous current dynamo having twomain magnetic poles the strength of which is substantially independentof the speed variations, in alternate arrangement with said mainmagnetic poles, two auxiliary poles, a two-pole armature relativelymovable at a variable speed within said main and auxiliary poles, twomain brushes on said armature, an auxiliary brush on said armaturebetween the main brushes, and means for producing in said auxiliarypoles two magneto-motive forces, one proportionate to the number ofrevolutions and the other approximately constant, said means comprisingtwo sets of field coils energizing said auxiliary poles, the first ofthe two sets of coils being connected to said auxiliary brush and to oneof the main brushes, the armature between said auxiliary and said mainbrush being affected by the magnetic lines of force of the main polesonly and the second of the two sets of coils being connected to said twomain brushes in such a manner that the magnetizing eect of said secondset of coils is opposed to the magnetizing effect of said first set ofcoils.

2. A variable-speed continuous current dynamo having two main magneticpoles the strength of which is substantially independent of the speedvariations, in alternate arrangement with said two main magnetic poles,two auxiliary poles with coils energizing said auxiliary poles, atwo-pole armature relatively movable at a variable speed within saidmain and auxiliary poles, two main brushes on said armature, and meansfor producing in said auxiliary field coils two electro-motive forcesrespectively, one proportionate to the number of revolutions and theother approximately constant, said means comprising an auxiliary brushbetween the two main brushes, one of said auxiliary field coils beingconnected to said auxiliary brush and to one of the two main brushes,the armature between said auxiliary and said main brush being affectedby the magnetic lines of force of the main poles only, and alsocomprising a suitably directed approximately constant voltage sourceintroduced into the circuit of the other of said auxiliary coils.

In witness whereof I aiiix my signature.

FRITZ xEssEnniNe.

